1. Field of the Invention
The present invention relates to an array substrate, a method of manufacturing the same, and a method of crystallizing silicon. More particularly, the present invention relates to an array substrate capable of improving current mobility and design margin of a switching element, a method of manufacturing the same, and a method of crystallizing silicon.
2. Description of the Related Art
A liquid crystal display (“LCD”) device, in general, includes a display panel having an array substrate, a color filter substrate, and a liquid crystal layer. The array substrate includes a plurality of pixels arranged in a matrix, each including a thin film transistor (“TFT”) and a pixel electrode. The color filter substrate includes a common electrode and corresponds to the array substrate. The liquid crystal layer is interposed between the array substrate and the color filter substrate. Liquid crystal molecules within the liquid crystal layer change orientations depending on the signals applied to the common electrode and the pixel electrodes, thereby changing an image on the display panel.
The LCD device is divided into an amorphous silicon (“a-Si”) LCD device and a poly silicon LCD device. The a-Si LCD device includes an a-Si TFT. The poly silicon LCD device includes a poly silicon TFT.
In the poly silicon LCD device, the poly silicon TFT is formed through a crystallization of an amorphous silicon.
The amorphous silicon is crystallized through a sequential lateral solidification (“SLS”) method. In particular, an irradiation of a laser beam is controlled using a mask that has a transmitting portion and a blocking portion. Size of a silicon grain is increased by a predetermined distance in a lateral direction to crystallize the amorphous silicon.
The transmitting portion and the blocking portion of the mask are extended in a longitudinal direction or a horizontal direction. Therefore, the poly silicon grain formed through the SLS method is extended in the horizontal direction or the longitudinal direction.
The current mobility of the poly silicon grain is increased in the extended direction of the poly silicon grain. That is, a channel direction of the TFT is substantially the same as the extended direction of the poly silicon grain.
Therefore, when the extended direction of the poly silicon grain is fixed, a location of the TFT is restricted, and a design margin of the TFT is deteriorated.